Program transmission over wires



Dec. 29, 1925' J. F. TOOMEY ET AL PROGRAM TRANSMISSION OVER WIRES Filed NOV. 11, 1922 objections.

Patented Dec. 29, 1925.

UNITED STATES PATENT OFFICE,

JOHN F. TOOMEY AND HENRY E. PHELPS, OF NEW YORK, N. Y., ASSIGNORS 'IO AMERI- CAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

PROGRAM TRANSMISSION OVER WIRES.

Application filed November 11, 1922. Serial No. 600,355.

7 '0 all 1 1/1 om it may concern:

Be it known that we, JOHN F. TOOMEY and HENRY E. PHELPS, residing at New York and New York, in the counties of NewsYork and Bronx and States of New York and New York, respectively, have invented certain Improvements in Program Transmission Over Wires, of which the following is a specification.

This invention relates to systems of communication and more particularly to systems for disseminating news, information, music or the like.

Various schemes have been proposed heretofore for program transmission. The only one of these schemes which has been exploited to any extent is radio broadcasting, that is, the broadcasting of news, information or entertainment by means of radio telephone equipment so that persons provided with suitable radio receiving sets tuned to the proper wave length may receive the transmitted entertainment or the like.

This method, however, has very serious 1n the first place, numerous broadcasting stations in the same area operate on wave lengths sufficiently close together to interfere with each other. Furthermore, radio telephonic transmission necessarily involves the use of a much wider band of the frequency spectrum-than is used for wireless telegraph purposes, and in view of the fact that the number of wave, lengths available for radio communication are necessarily limited it is undesirable that wave lengths necessary for commercial communication should be utilized for purposes of mere entertainment. Finally, in order to avail himself of the desired information or entertainment, each individual subscriber must provide himself with a radio receiving equipment which involves storing upon his premises expensive storage batteries which are constantly in need of re-charging, to-

' gether with a considerable amount of delicate and elaborate electrical apparatus, such as'coils, detectors, amplifiers, etc., all of which involve careful maintenance. Moreover, the radio receiving set as now known is, at its best, an inherently ugly thing, absolutely out of place in the home and requiring for its operation a net work of unsightly wiring.

Realizing the inherent limitations of radio broadcasting, proposals have been made to use existing wire systems, such as telephone, telegraph or power networks for program distribution purposes by transmitting carrier frequencies over such existing power or communication lines. Such a method however, would be extremely expensive as well as complicated, as it involves a very considerable reorganization of the telephone plant or power plant, and requires the use of quite complicated and expensive apparatus.

The ordinary telephone plant, however, ofl'ersunusual facilities for program dis trlbutlon purposes by the use of ordinary telephonic methods and without the employment of any high frequency or carrier meth ods of signaling. l/Vhen it is realized that the average subscribers telephone set is in use for telephonic purposes only during an extremely small part of the time it becomes apparent at once that if the telephone line, dur ng its idle periods, could be used for dissemlnating news, information or entertainment, the plant could be used much more economically and the information or the like to be distributed could be transmitted to the subscriber in the simplest manner possible. It may further be observed that the average subscriber to a distribution service, particularly a service for distributing entertainment, would only desire to avail himself of the service during the late afternoon or during the evening, at which times the average subscribers telephone is only used for social purposes and is rarely or never used for business calls.

Having these circumstances in mind, it is proposed by this invention to provide simple, practical and economical arrangements by which news, information, music or other forms of entertainment may be transmitted at ordinary telephonic frequencies from a central program station over subscribers telephone lines. It is also proposed by this invention to provide a system whereby the telephone subscriber may receive the pro gram service without interfering in any way with the use of his line for ordinary tele phone purposes. This invention also renders available a program distribution system in which the apparatus not only at the central station but more particularly at the subscriber's station will be extremely simple and economical and yet efiicient.

T11? invention may now be more fully understood by reference to the following detailed description thereof when read in connection with the accompanying drawlng 1n -which Figure 1 is a circuit arrangement illustrating a program distribution system as applied to an ordinary subscribers line involving manual switching, between subscribers, and Fig. 2 illustrates such a system applied to a subscribers line involving machine switching at the central office.

Referring to Fig. 1, L designates an ordinary telephone subscribers line terminating at one end at a subscribers station A and at the other end in a central oflice B. At the station A, the usual form of telephone set 10 is provided for ordinary telephonic purposes and a supplemental key K is provided for associating with the line a broadcasting receiving equipment comprising a loud speaking receiver 11 and other apparatus to be described later.

At the central station B, the line terminates in the usual type of switching jack J whereby telephonic communication may be established through the cord circuit C between the line L and other lines terminating at the exchange. Normally, the line L is connected over the contacts of a relay 12 to the jack J, but the circuit of the relay 12 is so arranged that the line may be disconnected from the jack J when the key K is operated and connected through a transformer 13 with a program distributing equipment common to a large number of lines. The central program equlpment 1tself is illustrated at D and is of a very simple type, consisting, in-its most fundamental form, of an ordinary telephone transmitter and energizing battery such as is in common use in telephone substations today.

At the central oflice, in addition to the usual line relay LR, a special relay SR is bridged across the line, the latter relay operating when the key K is actuated by the subscriber to energize the relay 12, which functions to disconnect the line from the jack J and connect it to the program equipment at D, at the same time applying a busy tone to the sleeve conductor of the jack to notify the central operator when testing the terminal that the subscriber is using the line for receiving the program service. The line relay LR is marginal and does not operate through the high resistance connection es tablished by the key K and will only operate when the line is closed through the low impedance telephone set 10 by taking the receiver from the switchhook.

If the subscriber should desire to use the line for ordinary telephonic purposes, the line relay LR will operate as soon as the receiver is taken from the hook, thereby causing the line lamp 15 to glow. At the same time it opens the circuit of the relay 12 to prevent the relay SR from actuating the relay 12 to disconnect the line from the jack J. The'operator, upon observing the glowing of the line lamp may establish a connection in the usual manner by means of a cord circuit C. If, upon an incoming call, the operator desires to establish a connection with the line L, the busy tone on the jack J may be disregarded if the subscriber is receiving program service and a connection established by inserting the plug of the cord C in the jack J. This operates the cut-off relay COR, which in turn disconnects the special relay SR and the line relay LR from the line.

At the subscribers station, the transformer 14, which serves to associate the loud speaking receiver 11 with the line, is provided with a condenser shunted by the high resistance winding of a polar relay PR. Owing to the high resistance of the latter, when the key K is thrown, only sufiicient current flows through the bridge, including the windings of the relays SR and LRat the central station to operate the relay SR, the line relay LR not being operated when the setis used for program purposes. The polar relay PR controls a relay 16, whereby the loud speaking receiver 11 may be dis connected from the line, even though the key K is actuated. The polar relay PR is so poled as to energize the relay 16 for this purpose only when battery is supplied to the line from the cord circuit, the battery connections through the windings of the relays LR and SR being reversed with respect to the cord circuit. Consequently, the relay PR disconnects the loud speaking receiver only when the operator inserts the plug of the cord circuit G into the jack J to establish an ordinary telephone connection. This obviates any possibility of ringing current actuating the loud speaking receiver and annoying the subscriber. A low resistance relay 17' is included in series with the subscribers set '10, said relay operating to disconnect the polar relay PR and loud speaking receiver 11 from the line L through an auxiliary relay 18 whenever the subscriber takes down the receiver to use his set for ordinary telephonic purposes. This arrangement is provided so that the special receiving equipment will be disconnected under these circumstances even though the subscriber should fail to restore the key K.

The detailed operation is as follows: Assuming that the subscriber at station A desires to receive the program service, the key K is actuated, thereby closing a. circuit through the winding of the high resistance polar relay PR, over the normal contacts of the relay 18, over the make contacts of the key K, over the line L, normal contact of the cut-ofi' relay COR and through the windings of the special relay SR and the line relay LR. The special relay SR is operated over this circuit but the current flow is not in a direction to operate the relay PR. The marginal line relay LR is not operated and hence the energization of the relay SR completes a circuit from ground, over the back contact of the line relay LR and front contact of the special relay SR, through the winding of the relay 12. The latter is energized to disconnect the line L from the ack J and connect the line to the program equipment at D, at the same time applying a busy tone to the sleeve conductor of the jack J to apprise the central office operator when testing the terminal that the subscrlber is receiving the distributed information. The actuation of the key K serves to connect the loud speaking receiver 11 with the line over the normal contacts of the relay 16, through the transformer 14 and the normal contacts of the relay 18. The subscriber is now enabled to hear by means of the loud speaker 11 the news, information, music or other entertainment distributed from the broadcasting station D.

If, while the line is thus in use a sufficiently urgent call should come 113130 the central switching oilioe for the line L, the.

" connects it to the tip and ring of the jack J.

' soon as the cord circuit is connected to the line and the relays SR and LR disconnected, the direct current supplied through the cord will be in such a direction as to actuate the polar relay PR and close the circuit of the relay 16, which at once disconnects the loud speaking receiver 11 from the transformer 14. The relay 16 is locked over its righthand front contact, right-hand back contact of relay 18 and lower make contact of key K, so that said relay 16 will be held up independently of the polar relay.

The subscriber may now be rung in the usual manner by the operator and upon removing the receiver from the hook, the talking circuit will be established to the central office. Direct current-from the central oliice battery flows through the cord circuit over the subscribers line and through the relay 17, this relay being energized as long as the re eiv r is. removed from the hook. The relay 17 completes the circuit of the relay 18, which disconnects the pro ram receiving a paratus from the line independently o? the key K and at its righthand contact opens a locking circuit of the relay 16, which is restored to normal. At the end of the conversation the subscriber may hang up his receiver, thereby giving the usual disconnect signal and deenergiz ing the relay 17 which (if the key K has not been restored) again connects the polar relay PR to the line. Current flows through the polar relay in such a direction as to energize and lock up the relay 16. As soon as the operator withdraws the plug of the cord C from the jack J, the cut-01f relay COR is deenergized, thereby again connecting the special relay SR and line relay LR to the line. The line relay LR is not energized but the special relay SR is energized in series with the polar relay PR. The current flow is not in such a direction as to operate the polar relay PR but the energization of the special relay SR again completes a circuit of the relay 12, which disconnects the line L from the jack J and connects it to the broadcasting station 1). Transmission from the program station may again he received by the loud speaking receiver 11 as soon as the subscriber restores the key K to unlock ithe relay l6, and then again actuates the tey.

If, while the line is being used for receiving distributed information, "the subscriber should desire to use the line for establishing a telephone call, the receiver may be removed from the hook, thereby energizing, in addition to the already encrgized relay SR, the line relay LR and the relay 17. The relay 17 actuates the relay 18 to disconnect the special receiving equipment independently of the key K. The line relay LR opens a circuit of the relay 12, which upon being deenergized, disconnects the line L from the program station and connects it to the jack J. The line relay LR at the same time completes a circuit of the line lamp over its front contact. The operator will answer the call by inserting the plug of the cord circuit C in the jack J, thereby causing the cut-oil" relay COR to disconnect the relays LR and SR from the line as before so that the relay 12 remains dcenergized with the line connected to the jack J. At the end of the conversation the subscriber may hang up his receiver and the apparatus may be restored to the condition for program reception in the manner already described.

Vv'hen the subscriber no longer desires to receive the program service he will simply restore the key K, thereby disconnecting the loud speaker and associated apparatus from the line and opening the circuit of the special relay SR. The latter, upon being deenergized, will open the circuit of the relay 12, which-will disconnect the line from theprogi'alpiJequipment at D and connect it to the AC 1 Fig. 2 illustrates an arrangement for applying program service to telephone lines terminating at a central ofiice equipped for machine switching. At machine switching ollices no operators will be provided to exercise discretion with regard to the urgency of incoming calls and in practice the circuits might be arranged either to exclude all incoming calls while the special program equipment is in use or to permit all incoming calls to interrupt the program service. The circuit illustrated in Fig. 2 is arranged so that when the line is in use for program receiving no incoming calls may be made. The subscriber himself, however, can interrupt the program service to make outgoing calls at any time by simply removinghis receiver from the switch-hook as in the case of the circuit shown in Fig. 1.

In this form 'of the invention the equipment at the subscribers station A, both for program receiving and for ordinary telephonic purposes, is identical with that shown in Fig. 1, except that the subscribers telephone set is provided with the usual form of dial 19 for operating the switching machinery at the central oflice. The program equipment at the station 1) and its association with the line L at-the central oflice is also identical with that illustrated in Fig. 1. The line L terminates at the central ofties for the purpose of establishing incoming connections in the usual form of connector bank (not shown) while, for the purpose of establishing outgoing connections the line terminates in the well known Keith line switch and its associated master switch. As these elements are well known in the art only a portion of the circuits thereof are illustrated and the detailed construction thereof need not be described. A marginal line relay LR is provided, as in the manual system, this relay being only operated when the receiver is removed from the switchhook. The line relay controls a double wound plunger magnet PM of well known construction, which performs the double function of acting as a cut-off relay and of operating the plunger SP to connect the line to the dialoperated switching machinery (not shown). The windings of the plunger magnet, as is well known, are so arranged that the upper winding, when energized, will cause the plunger P to operate. The lower winding,

however, will not operate the plunger SP but will only hold the plunger SP in operat ed position if it has already been operated. In addition to the marginal line relay LR, a special relay SR is provided, as in the manual system, said relay SR functioning, if the line relay LR is not energized, to complete the circuit of the relay 12, which disunderstood from the description of the opcration which is as follows: Assumin that the subscriber desires to receive distributed information'orthe like, the key K isactuated to connect the high impedance polar relay PR and the loud s eakin receiver 11 to the line as before. rect current circuit from battery through the line relay LR, through the winding of the special relay SR, over the upper contact of the plunger magnet PM, through a winding of the retard coil, to the ti side of the line L, upper make contact 0 the key K, left-hand contact of the relay 18, winding of polar relay PR, inner right-hand contact of relay 18, make contact of ke K, ring side of the line L, through the righthand winding of the retard c011 at the central station and over the lower contact of the I is esta lished a di-.

plunger magnet to ground, through the circuits of the master switch not shown). The current flowing through t is circuit is not sufficient to operate the line. relayLR and is not in such a direction'as to operate the polar relay PR. The special relay SR is operated, however, and completes a circuit for the relay 12, which disconnects the line L from the connector bank terminals and connects it to the station at D, so that distributed information from said station D is transmitted over the make contacts of the relay 12 and over the line L to the loud speaking receiver 11. It will be noted that while the line is in this condition a busy potential is applied to the sleeve conductor leading to the connector bank at the central oilice, over the lower front contact of the relay 12. Therefore, if, while the line is being thus used, some other subscriber desired to converse with the subscriber on the line L, the switching machinery (not shown) operated at the central station m a well known manner to establish connection with the line L, will find the busy potential upon the sleeve and will therefore fail to establish a connection with the line. The program service cannot be interrupted by an incommg call, therefore, if the special receiving equipment is in use.

If, while the program receiving apparatus is associated with the line by means of the key K so that the loud speaker 11 is being operated, the subscriber at station A should desire to use the line for ordinary telephone purposes the subscriber may remove the receiver from the switchhook, thereby establishing a low resistance connection over a circuit through the line relay LR, special relay SR and the relay 17. Relay 17 is energized and completes the circuit of relay 18, thereby disconnecting the loud speaking is maintained open.

receiver and associated equipment from the line independently of the key K. The marginal line relay LR is operated over the low resistance circuit through the substation set and its left-hand contact opens a circuit of the relay 12, which upon being deenergized disconnects the line from the central program station. Over its right hand contact the line relay LR completes a circuit through the upper winding of the plunger ma net PM (the portion of this circuit exten mg through the master switch is not shown). The plunger SP is actuated by means of the upper winding of the plunger magnet to complete a circuit from the line L over the switches controlled by the plunger magnet to the selector switches (not shown). The plunger magnet, upon being energized, CllS- connects the line relay LR and special relay SR from the line. Both relays are now deenergized so that the circuit of the relay 12 The actuation of the plunger switch completes a circuit from battery, through the lower winding of the plunger magnet and over the lnner r1 hthand contact of the plunger switch the complete circuit not being shown). The lower winding of the plunger magnet remains energized during the entire connection to hold the plunger in actuated position. The upper opera-ting winding of the plunger magnet is deenergized as soon as the armature of the line relay falls off.

The line circuit L, having been extended over the contacts of the Keith line switch under the control of the plunger SP to the tip and ring conductors extendin to the selector (not shown), the subscri er may manipulate the dial 19 in a well known manner, thereby transmitting lmpulses over the line to the switching machinery and establishing the desired connection. At the conclusion of the conversation, the subscriber at the station A hangs up his receiver. This causes a release of the switching machinery in a well known manner. As soon as the switching machinery is released the ground applied through such machinery to the conductor marked Release at the station B is removed therefrom, thereby opening the holding circuit extending over the inner right-hand contact of the plunger switch to the holding winding of the plunger magnet PM. The plunger magnet is now deenergized, releasing the plunger SP which disconnects the line from the switching apparatus. The plunger magnet, upon deenergizing, also connects the line relay LR and special relay SE to the line over the circuit previously traced. Relay 17 is deenergized when the receiver is hung up so that the loud speaking receiver and associated equipment is again connected to the line. The line relay LR remains deenergized because of the high impedance of the polar relay PR. The special relay SR is energized, however, and a ain com letes a circuit of the rela 12 so t at the hue may be again connected to the program receiving equipment and placed in condition for recfzeivlng the distributed informatlon as beore.

If the subscriber desires to terminate the reception of distributed information he merely restores the key K to normal, thereby o igning the circuit through the line relay L special relay SR and polar relay PB. The loud speaking receiver and associated equipment is now disconnected from the line at the contacts-of'the key K. The deenergization of the special relay SR results in opening the circuit of the relay 12, which thereupon disconnects the line L from the program equipment at station D and connects the line to the switchingterminals.

If, while the line is not being used either for ordinary telephone purposes or for program receiving a connection should be initiated through the switching machinery (not shown) for the line L, no 'busy ground would appear at the sleeve conductor of the connector bank and consequently the connector would make connection with the line terminals and complete a circuit over the sleeve conductor and the lower back contact of the relay 12 through the holding winding of the plunger magnet PM. The plunger SP would not be operated but the plunger magnet would be energized sufiiciently to disconnect the line relay LR and special relay SR from the line L, thereby preventing any possibility of the relay 12 being operated to disconnect the line from the connector bank. The battery current supplied over the line through the connector will flow in the opposite direction from that supplied from the line relay LR and special relay SR and therefore, if the subscriber should inadvertently or otherwise operate the key K after such a connection has been established and before'the receiver is re moved from the switchhook, the polar relay PR would be energized in such a direction as to operate the relay 16, thereby disconnecting the loud speaking receiver 11 from the line. If the subscriber, upon receiving a ringing signal from the connector switch, removes his receiver from the switchhook, the relay 17 will be operated, thereby in turn completing the circuit of the relay 18 and disconnecting both the polar relay PR and the loud speaker 11 from the line.

It will be obvious that the general principles herein disclosed may be embodied in many other organizations widely different from those illustrated without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. In a telephone system, a subscribers Ill) line terminating at one end at a subscriber's station and at the other end in a central otiice, a telephone set at said subscribersvstation, switching means at the central oflice whereby said telephone line may be interconnected with other telephone lines for ordinary telephonic intercommunication, a program transmittmg statlon normally disconnected-from said telephone line, aprogram receiving equipment at the subscribers station, means for connecting said pro- 2. In a telephone system, a subscribers line terminating at one end at a subscribers station and at the other end in a central office, a telephone set at said subscribers station, switching means at the central otlice whereby said telephone line may be interconnected with other telephone lines for ordinary telephonic intercommunication, a program transmitting station normally disconnected from said telephone line, a program receiving equipment at the subscribers station, means for connecting said program station over said telephone line to said program receiving equipment at will when the line is not being used for ordinary telephonic intercommunication, and means responsive to an incoming call from said substation at a time when the program is established for automatically disconnecting said line from said program station and connecting it to said switching means.

3. In a telephone system, a telephone line terminating at a subscribers station at one end and in a central oflice at the other end, a telephone set at said subscribers station, switching means at said central otiice for interconnectingsaid line with other lines for ordinary telephonic intercommunication, a program transmitting station normally disconnected from said line, special receiving equipment at the subscribers station for receiving program transmission, and means to associate said equipment with the line and to connect said program station to the line at the will of the subscriber.

4. In a telephone system, a telephone line terminating at a subscribers station at one end and in a central ofiice at the other end, a telephone set at said subscribers station, switching means at said central ofiice for interconnecting said line with other lines for ordinary telephonic intercommunication; a program transmitting station normally disconnected from said line, special receiving equipment at the subscribers station for receiving program transmission, means to associate said equipment with the line and to connect said program transmitting station to the line at the will of the subscriber,

and means operating when said telephone setis used for ordinary telephonic purposes to disconnect said special receivin equipment and said program station from t e line.

5. In a telephone system, a telephone line terminating at a subscribers station at one end and in a central oflice at the other end, a telephone set at said subscribers station, switchingmcans at said central office for interconnecting said line with other lines for ordinary telephonic intercommunication, a programItransmitting station n01 mally disconnected from said line, special receiving equipment at the subscribers station for receiving program transmission, means to associate said'equipment with the line and to connect said program station to the line at the will of the subscriber, and means responsive to an incoming call from said substation for disconnecting. said special receiving equipment and said program station from the line.

6. In a telephone system, a telephone line terminating at a subscribers station at one end and in a central ottice at the other end, a telephone set at said subscribers station, switching means at said central oflice for interconnecting said line with other lines for ordinary telephonic 'intercommunication, a program transmitting station normally disconnected from said line, special receiving equipment at the subscribers station for receiving program transmission, means to associate said equipment with the line and to connect said pro ram station to the line at the will of the su scriber, and means responsive to the connection of another line to said switching means to disconnect said special receiving equipment and said program station from the line and to connect the line to said switching means.

7 In a telephone system, a telephone line terminating at a subscribers station at one end and in a central oflice at the other end, a telephone set at said subscribers station, switching means at said central ofiice for interconnecting said line with other lines for ordinary telephonic intercommunication, a program transmitting station normally disconnected from said line, special receiving equipment at the subscribers station for receiving program transmission, means to associate said equipment with the line and to connect saidprogram station to the line at the will of the subscriber, and means associated with said switching means for indicating when the line is being used for program reception.

.8. In a telephone system, a plurality of station may be connected with a central oflice, switching means at said central oflice whereby any one of said lines may be connected with another line for-ordinary telephonic interconnection, a program transmitting station common to a plurality of said lines but normally disconnected therefrom, means whereby said program plurality of said lines when they are not being used for ordinary telephonic intercommunication, special program receiving equipment for each line in addition to the subscribers set, and means to connect said equipment to the line at will.

9. In a telephone system, a plurality of telephone lines adapted to be interconnected for telephone purposes, a program transmitting station common to a plurality of said lines andnormally disconnected therefrom, means for connecting said program station with a plurality of said lines when they are not interconnected for telephone purposes, special program receiving equlpment for each line in addition to the subscribers set, and means to connect said equipment to the line at will. 7

10. In a telephone system, a subscribers line terminating at one end at a subscribers station and at the other-end in a central ofiice, a telephone set at said subscribers' station, switching means at the central office whereby said telephone line may be interconnected with other telephone lines for ordinary telephonic intercommunication, a program transmitting station normally disconnected from said telephone line, means for connecting said program station with said telephone line-at will when the line is not being used for ordinary telephonic intercommumcation and means to give an indication at the central ofiice when program transmission is being received.

l1. Ina program transmitting system, a subscribers telephone line having a subscribers telephone set at the subscribers station and a program receiving circuit adapted to be bridged across said line at the subscribers station, said receiving circuit including a receiver for program currents, and means in said circuit to prevent ringing current from actuating said receiver.

In testimony whereof, We have signed our names to this specification this 10th day of November, 1922.

' JOHN F. TOOMEY.

HENRY E. PHELPS. 

